An efficient synthesis of a novel series of twelve substituted 2-amino-3-cyano-4H-pyran derivatives was achieved by a one-pot three-component cyclocondensation reaction of heteroaryl aldehydes, malononitrile and active methylene compounds catalyzed by iodine in aqueous medium under ultrasound irradiation. In comparison with conventional methods, our protocol is convenient and offers several advantages, such as shorter reaction time, higher yields, milder conditions and environmental friendliness. We have herein successfully demonstrated the synergistic outcome of multi-component reaction (MCR) and sonication to offer a facile route for the design of these derivatives.
Multicomponent reactions (MCRs) have emerged as key green tool in organic synthesis for their methodological simplicity. MCRs have made heterocycle synthesis more versatile. The most crucial molecule among the most often used heterocycles is pyridine, which is widely used in biological, industrial, and pharmaceutical sectors. In light of this, our mini-review highlights the literature on substituted pyridine synthesis published from the year 2016 to early 2022 via multicomponent approach.
An atom efficient protocol via a one-pot four-component cyclocondensation reaction catalyzed by copper(i) iodide in aqueous medium under ultrasonic irradiation has been developed for the synthesis of novel polysubstituted 1,4-dihydropyridines.
An efficient entry into the preparation of elusive, novel pyrano[2, 3‐e]pyrimidin‐amines and pyrano[2, 3‐d]pyrazol‐amines has been accomplished using citric acid as a green catalyst in aqueous medium at 25 °C. The strategy successively tolerates a variety of functional groups and interestingly, it is eco‐compatible, environment‐friendly, propitious and the products are obtained in excellent yields without chromatographic purification. The current methodology unfolds the benefits of citric acid as an effective, expeditious, economical, green catalyst and thus adheres to the principles of green chemistry. Ecstatically, the reaction was scaled to the gram level ascertaining the wide applicability of the protocol in academia and industry. The green metrics (E‐factor: 0.0497, Mass intensity: 1.1022, PMI: 1.0497 and Emw: 0.0497) for the reaction was also envisaged and the pathway was found to acquaint excellent green chemistry metrics.
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